The invention relates to a semiconductor circuit for an electronic unit.
Control technologies which rely on a two-wire bus as a communications medium are becoming increasingly important both in the industrial sector and in mobile applications, such as vehicles. Bus networks according to the CAN standard (CAN=Controller Area Network) are an example of this. In this case, a multiplicity of electronic units communicate with one another via only two conductor cores.
Without exception, such units perform their control task by means of a microcontroller. Particular bus protocol chips or protocol functionalities are provided for communication via the bus, and may be monolithically co-integrated in microcontrollers which are specialized for such applications, and function as a communicative transmitting/receiving link between bus and controller. They reduce the burden of tasks defined by the communications protocol on the microcontroller of the relevant unit and, in this way, considerably increase its availability and throughput for the actual control application.
Both the microcontroller and the bus protocol function require an operating voltage which must be kept within narrow limits, and as a rule is derived from a superordinate potential by means of a voltage regulator included in the control unit. If corresponding control units are used, for example, in means of transport, such voltage regulators must be particularly operationally reliable within wide temperature ranges and, above all, resistant to overvoltages and to interfering radio-frequency irradiation. Not all realization technologies for semiconductor circuits are equally suited to resistance to be optimized accordingly in practical operation. Particular so-called high-voltage technologies have been developed which take account precisely of the extreme loading situations in the case of voltage regulators, and which concern overload protection of the semiconductor chip against static and dynamic current, voltage and thermal stress. Correspondingly produced products have a high MTBF and an accordingly low failure rate.
It is also known to assign so-called watchdog circuits to microcontrollers or, for reasons of reducing costs and saving structural space, to co-integrate corresponding circuit functions as a subfunction of a microcontroller, using the production technology of the respective microcontroller. As a rule, these circuits are provided with means for generating and broadcasting a temporally defined reset signal to the microcontroller after the build-up of its operating voltage. However, problems arise when current-supplied areas are present on the chip of the microcontroller at different voltage levels and one of these areas may be subjected to high interference signal loading from the supply end. Corresponding solutions therefore demand very effective external protective measures for a corresponding semiconductor chip.
Moreover, discrete auxiliary modules for microprocessors are known which have means for monitoring at least one operating voltage, in order to generate a reset for the microcontroller for the purpose of a reliable program stop when the operating voltage leaves a predetermined tolerance window. They are predominantly produced using low-voltage technology in the range of 0.8 to 1.5 xcexcv.
German patent document DE 196 11 945.6, which was filed at the same time as the priority application DE 196 11 942.1, discloses a device for the bus-networked operation of an electronic unit with a microcontroller that takes account, inter alia, of the requirement of minimizing the total current consumption of a CAN during times of relative operational inactivity thereof.
The device comprises a specific semiconductor circuit having the bus function, of a communications transceiver and also a voltage regulator which can be electrically switched on and off. Both parts interact with one another such that the semiconductor circuit, in a specific operating state, outputs to the voltage regulator a signal which causes it to switch off, thereby also switching off the supply current generated at the output side to the electronics. In this state, only the semiconductor circuit and the regulator then draw very small quiescent currents from a superordinate supply potential; the microcontroller is deenergized. The semiconductor circuit which performs the transceiver function also includes additional functions therein for detecting bus faults and wake-up requests for reinitialization the microcontroller, as well as analog and digital functional components mixed.
Within the scope of that invention, it is proposed, inter alia, to integrate these functional components, together with the microcontroller and the bus protocol function monolithically on a single chip, thereby providing an electronic control unit that would essentially comprise, for example, three semiconductor modules. The latter include the (1) voltage regulator, the (2) single-body composite of microcontroller and bus protocol function, extended by the functional scope of the semiconductor circuitxe2x80x94to be understood conceptually as xe2x80x9cBus Application (BA) Controllerxe2x80x9dxe2x80x94, and also (3) an input/output interface which is connected downstream of the microcontroller in the direction of the application and serves to receive application-specific sensor signals and to drive requisite actuators, etc. The implementation and integration of such a semiconductor circuit is possible, but proves to be cost-intensive in relation to the range of applications that can be covered by such a special module.
An alternative to this would consist in integrating elements (1) to (3) to form a single xe2x80x9chyperchipxe2x80x9d. However, such a fully integrated xe2x80x9chyperchipxe2x80x9d based on a microcontroller is no less restricted in its applicability.
Thus, different hyperchip variants are necessary for different unit requirements. However, type spreading means that economies of scale for the desired cost reduction factor are limited. Furthermore, such a hyperchip is a customized module with consequent ties to a particular manufacturer. This may be a disadvantage, under certain circumstances, if there are second and trisource imperatives. Moreover, corresponding customized solutions render any standardization difficult, thereby diminishing the cost advantage. EMC problems are to be expected both in the case of the hyperchip and of the BA controller since interference from the bus can easily reach as far as the micro-controller. Necessary EMC protection measures may vary considerably from hyperchip to hyperchip or BA controller to BA controller, for different applications. Thus, apart from their costs, they must be implemented differently in different applications, so that the design rules repeatedly have to be observed anew. This inevitably opens up possibilities of faults as well. Furthermore, not every microcontroller technology that is of interest now or in the future is equally suited to incorporate circuit components which, in practice, either have to withstand residual interference voltage loading (which may be of the order of magnitude of the operating voltage of the microcontroller), or stress the chip material with spot power densities which, in the event of an fault, may reach a point near to thermal breakdown. These ambient conditions which result in such stresses are a familiar occurrence e.g. in industrial control technology and in means of transport.
The abovementioned problems increase exponentially as the system shrink dimension grows with advancing xcexcC technology. The spot power losses of, for example, drivers that may prevail on-chip are also becoming increasingly smaller. It may be assumed that the system shrink dimension of monolithic LS technologies will soon have reached 0.25 xcexcm. However, interface functions using 0.25 xcexcm technology are too sensitive to be connected directly with an industrial or vehicle environment, which is exposed to the risk, for example, of jump start, load dump and static overvoltage and to be operated with sufficient availability therein. Consequently, a structural-space and cost advantage that is achieved on the one hand forces additional means for the realization of protective functions, which additional means take up structural space and give rise to costs.
The object of the present invention, therefore, is to provide a semiconductor circuit for an electronic unit which avoids the above-mentioned disadvantages and problems and, in particular, enables a realization of modern two-wire-bus-controlled electronic units which is optimal in terms of space and cost.
The invention departs from prior approaches, and solves not only the problems of structural space, spreading and costs but also the additional problems of protecting the microcontroller against damaging ambient effects, and the need for numerous board connections on the microcontroller.
According to the invention, the voltage regulator and the semiconductor circuit driving the voltage regulator, with an interface function between two-wire bus and bus protocol module of the microcontroller are not co-integrated on the chip of the microcontroller using the low-voltage technology of the microcontroller. Rather, only the semiconductor circuit and auxiliary and expansion functions are co-integrated on the chip of the voltage regulator using the technology of the voltage regulator.
This technique obviates the need for the protective functions which were required just because the voltage regulator is provided on-chip with the microcontroller, in order to protect the latter against operational interfering effects on the voltage regulator (example: overheating, jump-start or load-dump punch-through by the regulator to the substrate).
To optimize costs, it is possible, in this way, freely to select microcontrollers having different bus protocol capability (for different specific applications), in order to cooperate with this functionality that is required equally in the vast majority of applications. For physical reasons, the technologies used for voltage regulators have substantially larger system dimensions than the low-voltage technologies for analog and digital application in A/D microcontrollers. For this reason, the robustness, which can be reproduced without difficulty in the voltage regulator, with regard to overvoltages, transients, radio-frequency irradiation, etc. is imported into the circuit function which fulfils the transceiver function between bus (functioning as xe2x80x9cantennaxe2x80x9d for interfering effects) and microcontroller, and consequently at the same time protects against all conceivable interference from the bus and from the power supply of the corresponding unit. In effect, this means that the high insulation requirements between the DC voltage-coupled two-wire bus and the highly sensitive low-voltage logic can be satisfied ideally in this way, while largely dispensing with cost-intensive protective means that take up structural space. The high demand for this function in a multiplicity of control units having performances that can be designed to be extremely varied overcomes the spreading problem, and makes it possible to achieve the cost advantages of very large-scale mass production. The end result is that a technical and structural optimization (in terms of complexity and costs) is thus achieved for the control unit as a whole by means of a well-restrained integration level, physically oriented to application practice, in comparison with modern LSI realization efforts.
Further advantages of the semiconductor circuit according to the invention are as follows:
The circuit is programmable.
The circuit contains programming means which permit one-time programming of at least one function of the circuit.
The circuit comprises a non-volatile memory area, designed as an EEPROM structure, for example.
The circuit comprises a non-volatile memory area and is programmable by data which determine at least one (characteristic) function of the circuit being able to be stored in the said memory area.
The circuit comprises an interface for the serial exchange of data and/or control signals between the circuit and at least the microcontroller which cooperates with the transceiver function thereof.
The driving and/or programming of at least one (characteristic) circuit function is possible via this interface.
The circuit means for providing at least one second supply voltage from linearly operating voltage regulator.
The circuit means for providing at least one second supply voltage from switched-mode voltage regulator.
The circuit means for providing at least one second supply voltage from a voltage regulator which is capable of a plurality of operating modes.
The voltage regulator which is capable of a plurality of operating modes can be operated both as a linear regulator and as a switched-mode regulator.
The circuit comprises means which allow the operating mode of the voltage regulator to be selected and/or changed in dependence on corresponding driving of the said voltage regulator.
The voltage regulator which can be operated as a switched-mode regulator is one which has an inductive energy store, the circuit being able to cooperate with at least the said energy store and a storage capacitor.
The switched-mode voltage regulator is a Buck-type step-down controller.
The voltage regulator comprises a freewheeling valve, which is current-conductive during the switch-off phases of the current flow for the purpose of magnetizing/charging the inductive energy store between one of the two terminals of the same and the reference-ground potential of the voltage regulation/ground potential.
The freewheeling valve is a diode path.
Freewheeling valve is a controlled electronic switch; in particular, a MOSFET transistor.
At least one of the electrodes of the freewheeling valve is routed to at least one particular terminal of the circuit and the said current conductivity can be realized by external circuitry of this at least one particular terminal.
The first current path electrode of the freewheeling valve is routed to a terminal of the circuit directly adjacent to the regulator output of the circuit and/or the second current path electrode is routed to a terminal directly adjacent to at least one ground terminal of the circuit.
The means for providing at least one second supply voltage can be activated and deactivated by a control signal with the aim of switching on and switching off, respectively, this supply voltage.
The means for the purpose of providing at least one second supply voltage configure two voltage regulators, namely a first voltage regulator for the purpose of providing a second supply voltage for the at least one microcontroller and a second voltage regulator for the purpose of providing a third supply voltage for the circuits of the control unit which cooperate with the said microcontroller/microcontrollers, these voltage regulators being configured in such a way that they can be activated and deactivated by means of a control signal.
The said means furthermore comprise control means, which cause the second and third supply voltages to be built up and/or reduced non-simultaneously in a defined manner, in dependence on a control signal.
The said control means are configured, or have an effect, such that in the case of activation, the second supply voltage for the at least one micro-controller can be built up before the third supply voltage for the circuits which cooperate with the said microcontroller/microcontrollers.
The said control means are configured, or have an effect, such that in the case of deactivation, the second supply voltage for the at least one micro-controller can be reduced after the third supply voltage for the circuits which cooperate with the said microcontroller/microcontrollers.
The two voltage regulators are independent of one another, and in this respect, only thermally coupled to one another and the circuit comprises means which have the effect that in the event of the substrate being heated, due to overloading, up to a critical temperature TLIM, the second voltage regulator is always deactivated before this temperature is reached and the first voltage regulator is deactivated only after this temperature is reached.
The at least one voltage regulator can be driven and/or programmed in order to be set to a specific output voltage from a plurality of selectable output voltages.
The operating mode of the voltage regulator which is capable of a plurality of operating modes can be selected and/or set by driving and/or programming.
The means for providing at least one second, fixed supply voltage, can be operated both by a regulating transistor, which is included in the said means, that is to say is circuit-internal, and in connection with a regulating transistor, which is external to the circuit, and, for this purpose, the circuit has a terminal for driving the control electrode of an external regulating transistor which cooperates with the circuit.
The operability of the means for providing at least one second, fixed supply voltage by a circuit-internal regulating transistor or by a circuit-external regulating transistor can be selected and/or set by driving and/or programming.
The circuit has at least one external terminal for the said driving or programming.
The programming of the means for providing at least one second supply voltage is possible by connecting up the at least one external terminal to a reference-ground potential, in particular to ground potential or a potential near to ground, or a potential that differs significantly from the reference-ground potential, or a supply potential.
The drivability of at least one function is provided by the interface.
The transceiver function is configured, both with regard to its transmitting and receiving means and with regard to a control means that it comprises, in such a way that it can optionally transmit and receive differentially in a two-wire manner or in a single-wire manner on at least one bus core with respect to a fixed reference-ground potential.
The transceiver function is configured, with regard to its transmitting and receiving means, in such a way that the slew rate thereof can be influenced, in particular can be adapted to the bus bit period and/or baud rate of the communication.
The circuit has a control path, via which the influencing of the slew rate by the microcontroller which cooperates with the transceiver function is possible.
The receiving means comprise a control interface, through which runs the abovementioned control path for the influencing of the slew rate.
The receiving means comprise means for detecting faults in the signal transmission in the bus network and for generating an indicative fault signal.
The receiving means comprise means for detecting faults in the bus network which are configured in such a way that they enable faults to be detected, and an fault signal to be output in the event of an fault, in a bus core-specific manner.
The means for detecting faults in the bus network comprise adjustable selection means which enable at least one indicative fault signal to be output; these means can be set to a preselectable number of successive bit signal faults as criterion for the outputting of the fault signal.
The receiving means comprise first selection means for faults which can be detected on the first bus core and second selection means for faults which can be detected on the second bus core, the first and second selection means being able to be set independently of one another to first and second numbers of successive bit signal faults as criteria for generating fault signals respectively assigned to the first and second bus cores.
The circuit has a control path, via which the setting of the abovementioned selection means by the microcontroller which cooperates with the transceiver function is possible.
The receiving means comprise a control interface, through which runs the abovementioned control path for setting up the selection means.
The control interface provided for influencing the slew rate and the control interface provided for setting the selection means are combined in one circuit structure.
The receiving means comprise at least one fault store, which can be set by an aforementioned fault signal.
The at least one fault store is part of the non-volatile memory area in accordance with claim 4.
The circuit comprises potential influencing means, which are connected to the transceiver function and serve to influence at least one signal level which is dominant in the case of transmission and/or discriminant in the case of reception.
The circuit comprises means for providing a further, circuit-internal supply voltage or a circuit-internal supply current for supplying the potential influencing means.
The circuit has a terminal for external monitoring and/or capacitive filtering of the circuit-internal supply voltage or of the circuit-internal supply current.
The circuit has a control path, via which the at least one microcontroller is capable of communication with the transceiver function and via which the potential influencing means can be driven.
The circuit comprises a control interface, through which runs the control path to the potential influencing means.
The control interface is part of, or is identical to, the interface.
The potential influencing means are configured in such a way that in the event of transmission, at least one of the two signal levels which determine the dominant bus level window can be shifted monotonically at least incrementally and/or decrementally.
In the context of the capability of influencing the two signal levels which are dominant in the case of transmission, both can be set or altered independently of one another.
The two signal levels which are dominant in the case of transmission can be set or shifted in such a way that the interval separating both levels is essentially maintained in the process.
The circuit has a signal-dedicated terminal as reference-ground potential busbar at least of the receiving means of the transceiver function.
The circuit has a current-dedicated terminal as reference-ground potential busbar at least of the means for providing at least one second, fixed supply voltage.
The circuit comprises a particular terminal as reference-ground potential busbar at least of the means for setting or alteration in the event of transmission of at least one of the two dominant signal levels which determine the bus level window.
The circuit has a particular terminal, via which the potential influencing means can be operatively connected to a reference-ground potential in the external environment of the unit carrying the circuit.
The circuit has, in the path of the said operative connection, means for protection against overvoltage and/or incorrect polarity and/or radio-frequency signal inputting.
The circuit is provided with an operating state, in which the means for providing the at least second supply voltage are switched on, the receiving means are activated and the transmitting means are deactivated and, in this respect, have no influence on the bus.
The circuit is provided with at least one operating state, in which the transmitting means of the transceiver function have no influence on the bus and in which the means for providing the at least second supply voltage are deactivated or switched off.
The circuit comprises, connected to the bus, wake-up identification means and control means, by means of which it can activate the means for providing the at least second supply voltage for the purpose of leaving this at least one operating state.
The circuit comprises control means which enable the microcontroller, which cooperates with the transceiver function, to put the circuit (back) into the abovementioned operating state.
The transceiver function is configured, with regard to its transmitting and receiving means, in such a way that the latter are tolerant to all possible fault states in and on the busline network, provided that all the bus subscribers behave compatibly with regard to the bus line network.
The circuit furthermore comprises, means for realizing a watchdog function at least for resetting the microcontroller which cooperates with the transceiver function for the purpose of monitoring a variable which is significant for the proper functioning or program execution of the said microcontroller.
The means for realizing a watchdog function comprise at least one timer and the circuit has at least one terminal for connecting up the watchdog function to at least one time-determining element.
The means for realizing a watchdog function are directly connected to the means for providing at least one second, fixed supply voltage.
The means for realizing a watchdog function and the means for providing at least one second supply voltage are connected to one another via a control path which proceeds from the interface.
The means for realizing a watchdog function are configured in such a way that they can additionally monitor, and reset, at least one further microcontroller of the control unit in respect of its proper functioning and program execution.
The circuit comprises means for generating and communicatingxe2x80x94after at least the supply voltage which feeds the at least one microcontroller is built upxe2x80x94a reset signal to the at least one microcontroller.
The circuit comprises means for outputting at least one inhibit signal in connection with the generation and transmission of at least one reset signal to the at least one microcontroller.
The circuit comprises means for monitoring at least one voltage from the first supply voltage (feeding voltage of the circuit) the at least one second supply voltage with regard to at least one limit value, and also means for outputting an interrupt signal or reset signal to at least the microcontroller, which cooperates with the transceiver function, when this limit value is undershot or exceeded.
The circuit has at least one particular input, via which a wake-up signal can be applied to the wake-up identification means, which are connected to the bus, in the operating mode; the circuit is furthermore configured in such a way that its behavior in response to a wake-up signal at this at least one particular input is identical to its behavior when a wake-up signal is received via the bus.
The circuit comprises autonomous means which are independent of the transceiver function, for detecting at least one wake-up signal in time periods at least of reduced or else increased activity of the at least one microcontroller.
The autonomous means have a plurality of inputs for receiving wake-up signals.
The autonomous means can be fed from the first supply voltage and can be operated independently of the means for providing at least one second, fixed supply voltage.
The autonomous means comprise at least one timer for the timing control of their function.
The autonomous means can be driven from the at least one timer of the watchdog function for the purpose of timing control of their function.
The autonomous means comprise at least one storage cell for storage of a detected wake-up event.
The autonomous means are capable of communicating with at least one microcontroller and are constructed such that they can be directly connected to such a microcontroller.
The autonomous means are capable of communicating via the interface, with the at least one microcontroller.
The autonomous means have at least one high-side and/or low-side switch for the at least periodic voltage supply of at least one wake-up sensor.
The autonomous means have at least one high-side and/or low-side current source for the at least periodic current supply of at least one wake-up sensor.
In a circuit the at least one high-side and/or low-side switch or current source can be controlled by the at least one timer at least indirectly in such a way that its or their switched-on duration tw is shorter than the repetition time ts of its or their switching on.
In a circuit the watchdog function and the autonomous means are configured with regard to one another in such a way that the at least one high-side and/or low-side switch or current source can be switched on for a predetermined switched-on duration tw at a repetition rate fs1/ts which is temporally interlinked with the repetition rate of a control signal which can be output by the watchdog function to the at least one microcontroller.
The switched-on duration tw and/or the repetition time or repetition rate ts or fs=1/ts and/or an interlinking factor are/is programmable.
The circuit comprises discrimination means which initiate the storage of a wake-up event when the wake-up event has been detected for the N-th time, where N =INTEGER ((td/ts)+1).
The number N is programmable and/or selectable from a set of predefined values.
The autonomous means are programmable, with regard to the truth condition of at least one of the plurality of wake-up inputs, from a fixed set of possible truth conditions and, in this respect, are flexible with regard to their circuit function.
The one-time programming of a circuit according to the invention may be initiated via the serial interface.
The circuit is programmable (configuration programming) with regard to at least one of the functions which are included in addition to the means for providing the at least second supply voltage, and/or the limit value(s) of the said function(s) and/or the time response(s) of the said function(s) and/or the truth condition(s) of the said function(s) or can be set to predefined values.
The programming of the configuration of the circuit can be stored as a closed data record in a non-volatile memory area.
The circuit comprises means which allow the abovementioned data record to be able to be read into the circuitxe2x80x94after the installation of the latter into the control unitxe2x80x94from another control unit having an already programmed circuit and the characteristic function of the circuit to be able to be cloned in this respect.
The non-volatile memory area of the circuit can be is read out and/or overwritten by the microcontroller, which cooperates with the circuit, via an interface.
The circuit has two terminals for the connection of two external terminating elements for the two bus cores and also internal bus fault detection means and internal backup terminating and changeover means, in order to alter the bus termination in the event of an fault.
The transceiver function of the circuit comprises adjustable bit period filters for optimizing the interference suppression to the communications baud rate.
The bit period filters are digitally adjustable.
Potential influencing means realize an adjustable offset voltage source, which is looped into that supply terminal of the transmitting means which is near to the reference-ground potential.
At least parts of analog action of the receiving means are connected in parallel with the constant-voltage-supplied transmitting means in terms of power supplying, with the result that the said offset voltage source is effective at the receiving end as well.
The potential influencing means realize a first adjustable offset voltage source, which is looped into the supply terminal, near to the reference-ground potential, of a switching output stage of the transmitting means which drives the bus core BUS_L, and a second adjustable offset voltage source, which is looped into a supply terminal, which is opposite in terms of potential, of a switching output stage which drives the bus core BUS_H.
The potential influencing means additionally realize a third adjustable offset voltage source, the latter and the previously mentioned second offset voltage source being referred or connected to supply potentials of different magnitudes.
The second and third offset voltage sources can be activated alternatively.
The offset voltage source (QSL) referred to the reference-ground potential and the effective offset voltage source remote from the reference-ground potential can be activated alternately only in chronological succession.
The circuit comprises means which allow activation of the second and third offset voltage sources in dependence on the transmission signal.
The potential influencing means comprise means for autonomous alteration of the setting of at least one offset voltage source over time.
Such an alteration is possible in dependence on the data signal at the transmitting end.
A clock signal, which can be drawn from the at least one microcontroller can be fed to the means for autonomous alteration of the setting of at least one offset voltage source.
The potential influencing means comprise regulating means which allow the influencing to be performed in accordance with a value specification, which can be received from the at least one microcontroller, in dependence on a potential which can be tapped on a bus core.
The potential influencing means comprisexe2x80x94independently of the transmitting meansxe2x80x94backup means which are connected or can be connected to at least one bus core and allow connection, keyed by the transmission signal, to the bus core of a regulated potential.
The potential influencing means furthermore comprise measuring means, which afford the acquisition of an fault quantity, caused by the backup means, for the purpose of compensation by regulating connection or computational allowance in the desired value specification for the regulation by the at least one microcontroller.
The potential influencing means comprisexe2x80x94independently of the transmitting meansxe2x80x94backup means which are connected or can be connected to at least one bus core and via which a connection which is keyed by the transmission signal is possible to the bus core by of an unregulated potential in accordance with a digital value which can be predetermined by the at least one microcontroller.
For the purpose of activating one of the backup means, the latter can be fed the transmission signal from the relevant core output stage via a changeover switch, which, if appropriate, disconnects the core output stage from the bus core.
The regulating means comprise a sampler, which is operatively connected to a bus core, and a holding element or a holding regulator.
The sampler is one which has two diode paths, the second diode path being provided for the compensation of temperature influences and/or of an fault voltage, caused by the sampling current flow, along the first diode path.
The potential influencing means are configured in such a way that they allow the influencing of at least one recessively discriminant signal level by the influencing of at least one threshold voltage in the receiver.
The receiving means have means for specifying two threshold values, which means are referred to a reference-ground potential busbar. Here, reference-ground potential busbar is operatively connected or can optionally be operatively connected to one of at least two alternative reference-ground potential terminals of the circuit.
The influencing is possible by means of an adjustable offset voltage source which lies in the supply current path, near to the reference-ground potential, of at least parts of analog action of the receiving means.
The reference-ground potential busbar of the threshold value specification means can be connected to the supply reference point, near to the reference-ground potential, at least of the parts of analog action of the receiving means.
The receiving means of the circuit have level discrimination means referred to a supply reference point. Here, this supply reference point is operatively connected to a reference-ground potential terminal or can optionally be operatively connected to at least two alternative reference-ground potential terminals of the circuit.
The potential influencing means comprise digital/analog conversion means and/or analog/digital conversion means.
The potential influencing means comprise digital/analog conversion means which can generate at least all the reference values, control and switching signals for potential influencing that is to be performed, where applicable, during transmitting and/or receiving operation of the transceiver function.
An offset voltage source referred to a higher supply potential is replaced in the circuit by a supply voltage source which is referred to a lower supply potential and can correspondingly be varied with offset capability.
The circuit is an integral part of an electronic control unit in which it is wired up or can be driven for only single-wire reception and only single-wire transmission (with only one line driver at the transmitting end).
The circuit is part of an electronic control unit provided for use in a means of transport.
The circuit is part of an electronic control unit provided for use in construction machines or hoists.
The circuit is part of an electronic control unit provided for use in automation technology.
The circuit is part of an electronic control unit provided for use in electrical installation technology or buildings technology.
The circuit is part of an electronic control unit provided for use in heating technology or air-conditioning technology.
The circuit is part of an electronic control unit provided for use in alarm technology, safety technology or access control technology.
The transceiver function of the circuit is designed for communication according to the CAN standard and for connection to a CAN bus line network.
The circuit is fabricated using homogeneous high-voltage technology.
All in all, then, the circuit can also comprise, in addition to at least one voltage regulator for the power supply of a control unit and a signal transceiver for communication via a two-wire bus, watchdog functions, various wake-up functions and an interface for serial data transmission between the circuit and at least the microcontroller which cooperates in a bus-communicative manner with the circuit. Via the interface, it is possible to exchange the cooperative control signals and/or data. Also provided are the capability of programming all the essential functions and/or their limit values and/or time responses, and also the capability of storing corresponding programming data in an optionally included non-volatile memory of the EEPROM type, for example.
The circuit can be produced cost-effectively using a homogeneous high-voltage technology, so that it is highly robust and resistant to possible interfering and overloading effects in the industrial and vehicle environment. Thus, it is especially suited to use in means of transport or industrial environments.
Exemplary embodiments of the invention are illustrated in the drawing and explained in more detail in the description below.
While the following description of the figures is based by way of examplexe2x80x94on an implementation for a CAN bus and, therefore, also uses designations introduced in this field, the invention nevertheless also encompasses other two-wire buses. It can therefore be used just as advantageously in correspondingly equipped control unitsxe2x80x94for example according to the J1850 Standard. This general applicability is taken into account in the drawing both by a mutual designation of the bus lines by BUS_H and BUS_L and a specific designation for the CAN application CAN_H and CAN_L. The description of the complex functionality is deliberately handled such that it retraces, for a person skilled in the art, the path on which the concrete solution in this case was found.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.